[Bug target/118075] New: [15 Regression] RISC-V: Miscompile at -O3 zvl 256 since r15-4746-g30435cc2610

[patrick at rivosinc dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118075

            Bug ID: 118075
           Summary: [15 Regression] RISC-V: Miscompile at -O3 zvl 256
                    since r15-4746-g30435cc2610
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: patrick at rivosinc dot com
  Target Milestone: ---

Testcase:
int a;
int b[14];
char c[14][14];
int main() {
  for (long f = 0; f < 14; ++f)
    for (long g = 0; g < 4; ++g)
      c[f][g] = 1;
  for (short f = 0; f < 014; f += 653115032 + 16745)
    c[f][f] = b[f];
  for (long f = 0; f < 4; ++f)
    for (long g = 0; g < 14; ++g)
      a ^= c[f][g];
  if (a != 0)
    return 1;
}

Commands:
/scratch/tc-testing/tc-compiler-fuzz-bisect/build-rv64gcv/bin/riscv64-unknown-linux-gnu-gcc
-march=rv64gcv_zvl256b -O3 -mrvv-vector-bits=zvl test.c -o user-config.out
QEMU_CPU=rv64,vlen=256,rvv_ta_all_1s=true,rvv_ma_all_1s=true,v=true,vext_spec=v1.0,zve32f=true,zve32x=true,zve64d=true,zve64f=true,zve64x=true
/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/qemu-riscv64
user-config.out

Found via fuzzer

First bad commit: r15-4746-g30435cc2610